Circuit breaker



Get. 11, 1938. w VER PLANCK ET AL 2,133,158

CIRCUIT BREAKER Filed Dec. 17, 1936 2 Sheets-Sheet l Joseph W. earhan, y iVwm f 4} I, Their Attorney.

Oct. 11, 1938. D. w. VER PLANCK ET AL C IRCUIT BREAKER Filed Deb. 17, 19:56

2 Sheets-Sheet 2 U y Inventor-81 Dennistoun W. Vew Planck,

Joseph W. Ssaman,

by)? CTJ Th ir- Attorney.

Patented Oct. 11,1938

UNITED. STATES CIRCUIT BREAKER Dennistoun W. Ver Planck, New Haven, Conn,

and Joseph W. Seaman, Upper Darby, Pa., assignors to General Electric Company, a corporation of New York Application December 1'7, 1936, Serial No. 116,384

8 Claims. 01. 200-147) Our invention relates to circuit breakers, more particularly to circuit interrupting devices of the I compression chamber type in which the circuit interrupting contacts are enclosed within a gastightly sealed compression chamber and has for an Object the provision of inexpensive and highly reliable interrupting devices of this character.

We have found that the pressure required to extinguish the arc is a direct function of the temperature of the entrapped gases, 1. e., at low temperatures only relatively low pressures are required and at high gas temperatures relatively high gas pressures are necessary to extinguish the arc. Thus by cooling the arc, quick extinguishment may be obtained with limited pressures and the construction of the compression chamber may be considerably less rugged.

In carrying out our invention in one form, we provide a pair of contacts, oneof whichis movable between open and closed circuit position, together with walls of pressure resistant material enclosing the contacts to form a compression chamber having a volume such that gas pressures of substantial magnitude are generated in the chamber by the heat of the arc formed upon separation of the contacts, and a plurality of spaced metallic members disposed adjacent the path of movement of the movable contact for cooling the arc whereby the relatively low gas pressures effect a quick extinguishment of the arc.

Interrupters constructed in accordance with the present invention have successfully interrupted currents in the neighborhood of 10,000 amperes at 450 volts without detrimental burning of the contacts.

For a more complete understanding of our invention, reference should now be had to the drawings in which Fig. l'is an elevational view, partly in section, of a multiple pole circuit breaker provided with interrupting units embodying our invention; Fig. 2 is a plan view, partly in section, and with certain parts broken away, of the circuit breaker shown in Fig. 1; Figs. 3, '4, and 5 aredetail views in exploded perspective of various elements of our improved interrupting unit; and Fig. 6 is a fragmental sectional view taken along the line 6-8 of Fig. 1.

Referring nowto the drawings, we have shown our invention as applied to a multiple pole circuit breaker of the type described andclaimed in a copending application of Winfield A. Atwood,

Serial No. 116,413, filed December 17,1936, entitled Circuit breakers", which app cation is as I i; signed tothes ame assignee as the p esent invention.. As shown, the circuit breaker comprises 8 base I formed of insulating material and provided with a'covermember Ii having a plurality of walls i2 which divide the circuit breaker into three poles, each pole being provided with an interrupting unit i3 embodying our invention. Since the interrupting units I! are identical in construction, only one will be described.

Each of the interrupting units comprises a plurality of walls arranged to form a gas-tightly sealed compression chamber, which walls comprise a pair of substantially L-shaped members i4 and i5 (Fig. 5) formed of conducting material, preferably die-cast aluminum, and a cupshaped closure member I6 which may be formed from drawn steel. As shown, the drawn steel cup I6 is provided with a slot I! in its lower wall into which slot extends the horizontal leg of the L- shaped member I 5, this leg being provided with a plurality of notches I8 (Fig. i) and 19 (Fig. 6 which engage the sides of the slot ii. The open face of the drawn steel cup i6 overlaps and is se- .cured to the sides of the upstanding portion of the member i 5, preferably by rivets 20 which extend through suitable apertures in the cupshaped member l6 and the L-shaped member II. If desired, a suitable sealing compound may be employed gas-tightly to seal the joint between the members l5 and ii.

As shown, the conducting member I! is provided with an aperture 2i extending therethrough and with a pair of semi-cylindrical grooves or bearings 22 .(Fig. 5) which extend from the aperture 2| to the outer edges of the member l5, and the conducting member II is provided with a recess 23 (Figs. 1 and 2) and with a pair of similar drical bearings.

Joumaled in the bearings formed by the grooves 22 and 24, we provide a rotatable shaft 11, the ends of which extend outwardly from the compression chamber formed by the members l4, l5, and i6, and the bearing portions of which are provided with grooves 2. in which suitable packing material 2! (Fig. 2) is located. Connested to'the portion of the shaft 21 intermediate its bearing portions. we provide a plurality of leaf springs which'extend through the arm-- ture 2| into the compression and constitute a switch arm, to the free end of which is connected an arcing member 3i, preferably formed of arc resisting material such as nickel,

for supporting a movable contact member 32. As shown, a flexible conductor 33' is secured at one I end to the arcing member 3! and the contact 32, the other end of the flexible conductor being securedto the L-shaped conducting member M by a suitable screw 33 (Fig. 1). g

- Arranged in cooperating relation with the movable contact 32, we provide a stationary contact 35 which is supported intermediate the ends of an arcing member 36 which extends siibstantially at right angles to the wall of the compression chamber formed by the conducting members M and I5 and which is supported on a conducting stud 31 extending through a pair of insulating bushings 38 and 39. As shown best in Fig. 6,

is more fully described in the above referred to- Atwood application, the terminal screw 43 on the conducting member M is connected by means of a suitable conductor (not shown) to the current responsive element of a tripping mechanism and this current responsive element is likewise connected by a conductor (not shown) to a terminal member 44 mounted on the left-hand end of the base l0. Thus, it will be seen that we have provided a compression chamber type interrupting unit in which the only extending parts constitute the extending ends of the rotatable shaft 21 and the extending end of the conductor stud 37 and in which one wall of the chamber serves as a portion of the electric circuit to provide means 1' for connecting the interrupting unit in an external circuit.

When the shaft 21 is rotated in a counterclockwise direction, the switch arm 30 and the contact 32 will be moved from the closed circuit position show'n in the drawings to an open circuit position in which the back of the arcing member 3i engages a stop pin 56 which is supported be:-

tween the legs of the U-shaped member 41, the yoke portion of which is secured to the conducting member 15 by a screw 48. Arranged along the path of movement of the movable contact 32, we provide a plurality of spaced members or plates 49 and 53, the plates 49 being formed of suitable magnetizable material, such as steel, and the plates 50 being formed of a material having a high heat conductivity such for example as copper. As shown best in Fig. 4, the plates 49 and 50 are provided with extending ears 52 which engage suitable notches (not shown) in the opposite walls of a supporting member 53 formed of suitable insulating material. The lower wall of this supporting member 53'is provided-with an aperture 54 through which the insulating bushing 39 extends, the lower wall of the member 53 being clamped betweenthe insulating bushing 38 and the horizontally extending portion of the conducting member l5 (Fig. 1) As shown, the upper portion of the insulating support 53 is connected to the outermost ends of the U-shaped member M. In order efiectively to insulate the extending cars 52 from the drawn steel cup it, an insulating shield 55 is provided within which the insulating support 53 nests, the lower wall of the insulating shield 55 resting on the lower wall of the drawn steel cup I5, I

the recess 57 and the interrupter unit may then be secured to the base. by suitable screws (58) which extend through apertures in the base member l0 and threadedly engage the conducting member I l. An insulating barrier 59 is disposed adjacent the right-hand end of the interrupter unit effectively to insulate the drawn steel cup it from the conductor 4i and the terminal member 42 and the recess 57 may then be filled through the aperture 56 with a suitable insulating compound 5911. which is fluid at high temperatures, but solid at normal temperatures.-

The interrupting unit l3 for the center pole of the circuit breaker difi'ers from the interrupting-units for the outer poles of the circuit breaker only in that both ends of the shaft 2'! extend outwardly from the interrupting unit for the center pole, while only the inner ends of the shafts 21 extend from the interrupting units for the outer poles. As is fully described in the above referred to Atwood .application, the interrupting units for the three poles of the circuit breaker are arranged on the base H1 in side by side relation with the shafts 21 in spaced, axial alinement. As shown, the extending ends of the shafts 21 are non-circular or square in accordance with the invention described and claimed in the said Atwood application and a pair of insulating cranks or disks 60 are disposed in. the

spaces between the adjacent ends of the shafts and provided with non-circular apertures 6| (Fig. 3) into which the non-circular ends ofthe shafts 21 extend. It will be apparent that when the crank disks 6!! are rotated, the shafts 21 will be simultaneously operated to actuate the movable contacts of the three interrupter units be tween their open and closed circuit position.

Although our invention is not limited thereto, the circuit breaker is preferably provided with a combined manual and automatic mechanism for rotating the crank discs- 60, which operating mechanism is of the type described and claimed in the above referred to Atwood application. Since the detailed construction of this operating mechanism forms no part of the present invention, it is not deemed necessary herein to show or describe the mechanism further than to say that the'mechanism isiarranged to rotate the crank and 35 in the closed circuit position shown, it will be assumed that an overload condition of shortcircuit magnitude'occursand that the operating mechanism is thereby influenced as described in the above referred to Atwood application so as to eflect operation of the movable contact 32 to its open circuit position. As the contact 32 is separated from the contact 35, an arc is drawn therebetween which heats the air or gas entrapped within the compression chamber so as to generate a pressure therewithin. The volume of the compression chamber is so proportioned that the heat of the arc generates a pressure of considerable magnitude and, as explained in the Walle Patent No. 2,047,842 issued July 14, 1936, the resistance oi the arc increases rapidly with an increase in the" pressure. If the pressure increases to a sufilciently high value, the resistance of the arc will become so great that the arc can no longer exist. We have found, however, that the pressures necessary to efiect extinguishment of an are, produced under the voltage and current conditions for which our improved interrupter is designed, are so great, due to the high temperatures generated, as to cause rupture of the compression chamber walls unless an expensive, heavy wall structure is provided. 'Ac- I cordingly, the metallic members 49 and 50 armembers 48 and 50 assist in efiecting extinguish- In addition, it will be remembered that the ,1

ment of the arc. As is well understood in the art, subdividing an arc into a plurality 01 short arcs, increases greatly the instability of thearc and although the compression chamber and the spaced metallic members 49 and 50 are apparently directed toward diametrically opposite results one tending to produce high temperatures and pressures and the other tending to limit the temperatures and pressures, we have found that by properly proportioning the compression chamber and the number and spacing of the metallic plates, an interrupting unit may be provided which efiects a much quicker extinguishment of the arc than either a conventional compression chamber interrupter or a conventional are split? ting device.

It is, of course, necessary that the are be moved quickly into engagement with the metallic members l9 and 50 and accordingly the conducting stud 31, the are members 36, the contacts 32 and metallic plates 49 are formed of magnetizable ma terial and accordingly these plates form a low reluctance path for the magnetic fiux surrounding the arc and the resulting magnetic attraction assists in quickly moving the are into engagement with the plates. I

As stated above, the plates SI are formed 01' a material-having a high heat conductivity, such for example as copper, in order to improve the cooling properties of the plates. It will be understood, however, that our invention is not limited tothe specific arrangement shown of magnetizable and non-magnetizable plates, and ii desired all or the plates 48 and 50 may be formed of magnetizable material. Likewise, if additional means is provided for quickly moving the are into engagement with the spaced metallic plates, all

of the plates 49 and 50 may be formed of copper or other non-magnetizable high heat conductivity material.

In order to equalize the pressures generated by the short are sections between the plates 49 and 50, each of these plates is provided with a small aperture 63.

Whilewe have shown a particular embodiment oi our invention, it will be understood, of course, that we do not'wish to be limited thereto since many modifications may be made and we, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent 0! the United States, is:

1. An electric circuit interrupter comprising a stationary contact, a movable contact arranged to engage said stationary contact, and a plurality of spaced arc extinguishing plates arranged along the path of movement of said movable contact and extending substantially at right angles to the path of movement of said movable contact, a plurality of said plates along the initial part of the opening movement of said movable contact being made of magnetizable material to move the are formed between said contacts into said plates,

and the remaining plate being made oi a nonmagnetizable material having high heat conductivity to cool the arc.

2. An electric circuit interrupter comprising a stationary contact, a pivotally mounted contact arm bearing a movable contact arranged to engage said stationary contact, and a plurality of parallel spaced arc extinguishing plates arranged adjacent substantially the entire path of movement of said movable contact and extending substantially at right angles to the path of movementgof said movable contact, a plurality of said plates along the initial part oi the opening movement of said movable contact being made of magnetizable material to move the are formed between said contacts into said plates, and the remaining plates being made of a non-magnetizable material having high heat conductivity to cool the arc.

3. An electric circuit interrupter comprising a stationary contact, a pivotally mounted contact arm bearing amovable contact arranged to engage said stationary contact, a plurality of parallel spaced arc extinguishing plates arranged adjacent substantially the entire path of movement of said movable contact and extending substantialLv at right angles to the path of move ment of said movable contact, a plurality oi said plates along the initial part of the opening movement of said movable contact being made of magnetizable material to move the are formed between said contacts into said plates, and the surface of said first supporting member to close said aperture and form an arc chamber, hearings on said supporting members, a shaft mounted in said bearings extending across said aperture, a stationary contact in said chamber, a contact arm secured to said shaft carrying a movable contact cooperating with said stationary contact,

a terminal on said second supporting member,

means electrically connecting said movable contact to said terminal, and operating means for said movable contact connected. to said shaft.

5. An electric circuit interrupter comprising a closure member open at one end, a supporting member made of electrically" conducting material in said closure member having a portion closing the open end of said closure member, said portion being provided with an aperture,' a second supporting member made of electrically conducting material fitting onto the outer surface of said first supporting member to close said aperture and form an arc chamber, bearings on said supporting members, a shaft mounted in said bearings extending across said aperture, a stationary contact in said chamber, a contact arm secured to said shaft carrying a movable contact cooperconnections for said movable contact are made with said second supporting member, and' operating means for said movable contact connected to said shaft. l

6. An electric circuit interrupter comprising a closure member open atone end, asupporting member made of electrically conducting material in said closure member having a portion closing the open end of said closure member, said portion being provided with an aperture, a second supporting member made of electrically conducting materialfitting onto the outer surface of said first supporting member to close said aperture and form an arc chamber, bearings on said supporting members, a shaft mountedin said bearings extending across said aperture, a stationary contact in said chamber secured to said first supporting member in electrically insulated relation thereto and having a portion extending through said first supporting member to the exterior of said are chamber, a contact arm secured to said shaft carrying a movable contact cooperating with said stationary contact, and operating means forsaid movable contact connected to said shaft in electrically insulated relation therewith.

7. An electric circuit interruptercomprising a closure member open at one end, a supporting member made of electrically conducting material in said closure member having a portion closing the open end of said closure member and gas tightly connected to said closure member, said portion being provided with an aperture, a second supporting member made of electrically conaiaaiea' ducting material fitting onto the outer surface of said first supporting member to close said aperture and form a gas tightly sealed arc chamher, said supporting members being provided with registering recesses forming bearings, a shaft mounted in said bearings extending across said cally insulated relation thereto and having a portion extending through said first supporting member to the exterior of said are chamber, a

contact arm secured to said shaft carrying a movable contact cooperating with said stationary contact, a flexible conductor connecting said movable contact to said second supporting member whereby electrical connections for said movable contact are made with said second supporting member, operating means for said movable contact connected tosaid shaft in electrically insulated relation therewith, and a base and cover of electrically insulating material inclosing, said supporting and closure members.

8. An electric circuit interrupter comprising a closure member open at one end, a supporting member made of electrically conducting material in said closure member having a portion closing the open end of said closure member and gas tightly connected to said closure member, said portion being provided with an aperture, a second supporting member made of electrically conducting material fitting onto the outer surface of said first supporting member to close said aperture and form a gas tightly sealed arc chamber, said supporting members being provided with registering recesses forming bearings, a shaft mounted in said bearings extending across said aperture, said second supporting members being provided tinguishing plates arranged adjacent the path 50 of movement ofks'aid movable contact, a plurality of said plates along the initial part of the opening movement of saidmovable contact being made of magnetizable material and the remaining plates being made of a. non-magnetizable material.

DENNIS'I'OUN W. 'VER PLANCK. JOSEH W. S N

' with a recess registering with said aperture, a 40 

